1. Field of the Invention
The present invention relates to air ducts having openings to allow air to flow from the duct, and more particularly to flexible air ducts, systems and methods which utilize flexible internal membrane structures in conjunction with a duct.
2. Background Information
Fabric ducts made from a sewn, pliable material have gained popularity as an inexpensive conduit to move air when compared to the more expensive, traditional sheet metal ductwork. A blower at the inlet of the duct is activated to supply air as needed. The air discharged from the blower inflates or travels through the duct to create a radially expanded tubular conduit that conveys the air the length of the tube. The pliable wall of the tube may be perforated along a length of the tube for dispersing air from within the duct into the areas being ventilated. Pliable air ducts are often suspended from a horizontal cable or track mounted just below the ceiling of a building.
Air ducts and systems having a pliable wall with perforations or permeable spaces to allow air to escape the duct are known. Also known are air ducts which include an internal membrane or liner which controls the direction of flow of the air. An example of an air control system having an inner membrane within a fabric duct can be found in U.S. Pat. No. 5,111,739. While such patented air flow controls and other systems may have useful features, there is room for improvement.